Material Handling Equipment

In document Guidelines for Warehousing Health Commodities (Page 65-69)

Material Handling

Equipment

Pallet Lift Truck Types

Pallets lift trucks are available in many variations and configurations. However, to describe each type and classification is beyond the scope of this document. In the following section, you will learn more about a few of the more popular and practical types of material handling equip-

ment—often called storage and pallet retrieval systems—used in public- health warehousing today.

Table 9 lists some general categories of pallet lift trucks, based on lifting height and aisle space availability: Table 10 lists the typical trucks bought and used, including their capabilities. These trucks were specifi- cally selected because they have all the capabilities required for public- health warehousing; they are also

practical and widely available. If you already know the requirements and constraints of your warehouse, such as your aisle width and needed height lift, table 10 can help you decide which truck is the most suitable for your operation.

As with the aisle width and lift height, every decision must also include the cost element. While buy- ing a narrow-aisle reach truck may seem like the best option, because it has the most flexibility, remember the cost of this truck is more than twice the cost for the medium-lift height equipment; and, exponentially, more than a simple hand pallet truck. In addition, the maintenance and up- keep required is more complex and expensive.

The maneuvering space needed to operate lift trucks effectively is critical when planning and designing warehouse operations. All trucks have two turning radii: outside and inside. The outside radius is measured by the overall swing of the truck frame to

Table 9. Lifting Height & Aisle Width

Lifting Height Aisle Width

Low-lifts Wide-aisle trucks

• Pallet can be lifted 0.10 to 0.18-plus meters • aisles 3.5m and up above the floor

Medium-lifts Narrow-aisle trucks

• Pallet can be lifted and stored on racks up to • aisles 2.5m – 3 m three shelves high

High-lifts Very narrow–aisle truck

• Pallets can be lifted and stored on racks up • aisles 1.5m –2.5 m. to and greater than five shelves high.

Table 10. Trucks Types and Their Capabilities

Pallet Jack Walkie Stacker Counterbalance Lift Truck Narrow Aisle Reach Truck Capabilities Manual Electric Electric Only Diesel CNG Electric Electric Only

Outdoor Only Use X

Indoor Only Use X X X X X

Outdoor & Indoor Use X

High Lift Capabilities X X X X

Medium Lift Capabilities X X X X X

Low Lift Only X X

Wide Aisle X X X X X X X

Narrow Aisle X X X X

Very-Narrow Aisle X X

Average Cost Range

(in US Dollars) $500 $2,000 $30,000 $30,000 $25,000 $40,000 $60,000

the furthest point of the rear frame. The inside radius, or the pivot point, is usually 0.08 to 0.10 meters outside the truck drive wheels (front wheels). Thus, this equipment cannot pivot within its own footprints.

To calculate the turning radii for a full right-turn angle (in metric) with a pallet using 0.15 meters for operating clearance, do the following: 1. Use manufacturer listed right-turn angle (forklift) + length of pallet + operating clearance (0.15 meters) = full right-turning radius, in meters. 2. Example: Lift truck right-angle

turn (2 meters) + length of pallet (1.2 meters) + operating clearance (0.15 meters) = total (3.35 meters).

Figure 17. Right-Angle Turning Radii

Every piece of equipment has different specifications. The equipment manu- facturer should always be contacted to provide the exact dimensions of the truck you are interested in and to gather more detailed information about the turning radii. In general, managers need to plan for right-angle stacking and cross-aisle maneuvering calculations, based on truck turning radii, truck frame configuration, and unit load length and width.

Below pallet jacks, walkie stacker’s, counterbalance lift trucks and narrow aisle reach trucks are described in fur-

ther detail. Each has an illustration, pros and cons, as well as sample aisle width requirements for each type of equipment. At the end are links to manufacturer websites that can provide more specific detail on these pieces of equipment as well as others that have not been discussed.

Pallet Jacks

Pallet jacks are manual or use electricity (see figures 18 and 19). The manually operated low-lifts are usually called pallet jacks or hand pallet jacks. This type of low-lift is flexible; it can be a real workhorse for a facility. Both the manual and electric model low-lifts operate from the floor, are self-loading, and fit between the top and bottom boards of a double-faced pallet. The manual pallet jack is principally used whenever loads, grades, and distances are small enough that a forklift or another type of power truck–type equipment is not needed. It has a fully sealed, cast iron block hydraulic pump (self-contained). The forks (approximately 0.15 meters wide) come equipped with integral slides that offer rigidity and easy pallet entry and exit. It is user-friendly equipment that requires little training; it can be used throughout the warehouse, loading docks, or inside all kinds of trucks. It provides exceptional maneuverability and flexibility of operation, and is comparatively much lower in cost and maintenance expenses than any other pallet handling equipment.

Figure 18. Manual Low-Lift Pallet Jack

The electric-powered pallet jack, also called walkie low-lift truck, is a hybrid of pallet jacks. An on-board rechargeable battery (see figure 19) powers these trucks. The batteries provide the power for the lifting and powering and transporting motions. The speed and load capacity varies with each model. Average speed for this type of walkie is about 6 kilometer per hour (kph). Again, many different models and sizes are available. The powered walkie- type pallet jack is used in situations similar to the manual pallet jack. However, the basic difference is that the powered truck can transport heavier loads, over greater distances, and at faster speeds. The electric low-lift equipment provides great maneuverability and is able to make tight turns. Using a walkie-type, the operator can see the fork tips for pallet entry; the battery swings out for easy, quick maintenance checks.

Figure 19. Electric Low-Lift Truck

SAMPLE AISLE WIDTH REQUIREMENTS

The usual required dimensions of a right-angle turn for a low-lift hand pallet jack range from 1.5–2.1 meters and for low-lift electric pallet jack range from 2.0–2.5 meters. These types of trucks are in the very narrow–aisle width category. Again, these required dimensions will vary, depending on the type of pallet jack selected; it is essential to review all the required dimensions with the manufacturing representative or engineer during the planning and selection process.

Walkie Stackers

Walkie stackers are a walk-behind pallet truck with a mast for lifting pallets up to heights over 4.5 meters. They are used when lift heights do not exceed 4.5 meters and a larger, more expensive forklift is not needed. They are used indoors on flat concrete floors, but they can be ordered with larger wheels that can operate on more uneven floors. The two types of commonly used walkie stackers are the walkie straddle stacker and the walkie reach stacker, both electrically powered by batteries. Unlike the counterbalance truck, the walkie straddle and walkie reach truck work within narrow stacking aisles. The efficiency and economy of these types of forklifts has been shown in actual field use for many years, under many different conditions.

WALKIE STRADDLE STACKER

Walkie straddle stackers use straddle legs to distribute the load weight. The legs allow the truck to straddle the pallet. These are good trucks to use for floor stacking, because the straddle legs allow closer pallet stacking (see figure 20). When they are used in conjunction with pallet racking, it is important to design the racks with enough space to allow for the wider straddle legs when loading pallets on and off the racks. Lifting heights start at 2.6 meters and go up to 4.8 meters.

Figure 20. Walkie Straddle Stacker

Walkie Reach Stacker

Walkie reach stackers are a variation of the straddle truck. It is more maneuverable than the standard forklift trucks and can usually operate in smaller spaces. For operations that require more versatility because of different load sizes and challenges within the facility, the walkie reach stacker may be a better fit for the facility’s needs. Reach trucks have a scissors-reach mechanism that moves the fork carriage forward into the load (see figure 21). Lifting heights start at 2.5 meters and can go as high as 4.54 meters.

Figure 21. Walkie Reach Stacker

SAMPLE AISLE WIDTH REQUIREMENTS

To complete a 90° turn within the aisle, with a 1.22 meter × 1.02 meter pallet, for either the standard walkie straddle stacker or walkie reach stacker, the right-angle stack dimension is 2.25 meters. If you add 0.15 meters for operating clearance, the total is aisle width requirements start at 2.5 meters. This assumes a 90° turn within the aisle with a load.

Counterbalance Lift Trucks

As the name implies, a counterbalance lift truck uses a counterbalance near the back of the truck to stabilize loads that are being transported or lifted to a storage area and retrieved. Counter- balanced lift trucks can be powered by either an internal combustion engine— gas, diesel, or liquefied petroleum gas (LP gas), or by a battery. With a capacity of 1,360-plus to 2,721-plus

kilograms, counterbalance trucks work well for dock, cross-dock, and dock-to-stock applications.

Counterbalance lift trucks offer a wide range of masts and attachments to handle all types of loads (see figure 22). Today, most lift trucks accom- modate ergonomic driver control and have relatively easy access for main- tenance. Additionally, some trucks have a full driver cab. The counter- balance lift truck, a very flexible piece of equipment, is considered to be the backbone of the warehouse industry.

Figure 22. Counterbalance Lift Truck

SAMPLE AISLE WIDTH REQUIREMENTS

To complete a 90° turn within the aisle, with a 1.22-meter × 1.02-meter pallet, the most common counterbal- anced lift truck requires approximate- ly 3.35 meters plus .15 meters for clearance for a total of 3.5 meters.

Narrow-Aisle Reach Trucks

Lift truck manufactures have devel- oped variations on lifts that can oper- ate effectively in narrower aisles. The most commonly used narrow-aisle design is called a narrow-aisle reach truck. Narrow-aisle reach trucks are always battery operated, and many accept attachments to meet all types of special handling requirements. Narrow-aisle reach trucks have forks that reach out beyond the stabilizing legs into the racking, which allow these trucks to lift to heights greater

than 10 meters, while still working in very tight aisles (see figure 23). While these trucks are excellent for use indoors, reach trucks are not suitable for work outside because of their low clearance and electric power systems, which can be harmed if the truck is regularly shaken while oper- ating on uneven surfaces.

Figure 23. Narrow-Aisle Reach Truck

SAMPLE AISLE WIDTH REQUIREMENTS

To complete a 90° turn within the aisle, with a 1.22 meter × 1.02 meter pallet, the narrow-aisle reach truck can operate in a 2.4 meter aisle plus .15 meters for clearance for a total of 2.54 meters. This is almost 1 meter less than the aisle space required for the counterbalance type.

GENERAL CONSIDERATIONS FOR ALL WALKIE STACKER’S OR REACH TRUCKS

Because the front wheels of the outrig- ger are much smaller than the other types of counterbalance equipment, they are not designed for crossing dock plates, or for jobs that require traveling over rough terrain: uneven cement floors, outside work with small stones on the surface, etc. For this type of equipment to function safely and productively, the surface for straddle trucks must be fairly smooth and free of debris and holes. Because of these limitations, the facility

may need other types of equipment for a specific job such as—

• for loading and unloading trucks • for outside jobs.

Rolling Warehouse Ladders

Rolling warehouse ladders provide a stable, transportable platform for maintenance, stock, and order pick- ing; and for many other warehouse and non-warehouse functions. This equipment has features, such as adjustable floor levelers and anti-skid steps (see figure 24). Rolling ware- house ladder sizes can range from two steps to 15 steps; and 0.508 meters to 4.8006 meters in overall height. Additional key features include— • Slip-resistant perforated tread: This

surface has maximum slip resistance and comfort when sitting or kneeling on steps

• First-step actuated locking system: This feature locks the ladder in place when a person steps on the first step. The step-lock feature is standard on most models.

• Heavy 1 1/16 -inch diameter tubular construction: In harsh environments, the tubular construction provides superior strength, as well as being both durable and long lasting. • Durable powder coated paint finish:

This type of finish is baked on in colors, such as industrial gray or safety yellow. It provides a premium quality scratch-resistant finish that is both durable and long lasting. In addition, warehouse ladders are available in steel or aluminum. They are also available in various degrees (48°–56°) of stairway slope for easy forward ascent or descent, commonly known as stairway slope warehouse

ladders. One reason to use these ladders is that the ladder has the feel of a stairway, so the workers are comfortable and feel safe climbing up and down the ladder steps.

Figure 24. Warehouse Rolling Ladder

Some facilities can implement an effective rack or bin system by using only a rolling warehouse ladder. If the size of the facility, or the expense of certain material handling equipment, is a constraint and the warehouse cannot accommodate any type of pallet lift equipment for storage and retrieval activities, warehouse rolling ladders (see figure 24) may be adequate for actual storage and retrieval of small items. The rolling ladders can also be used for other essential warehouse requirements; managers may need to keep rolling ladders in the warehouse to supplement their day-to-day necessities. They are also useful as a backup if other material handling equipment is unavailable. For additional information about to the equipment listed in this appendix, access the following web sites: http:// www.yale.com/ (Yale Materials Han- dling Cooperation) or http://www. hyster.com/ (Hyster Forklifts), both with locations in several countries), and http://www.mit-lift.com/ (Mit- subishi Fork Lift Trucks).

In document Guidelines for Warehousing Health Commodities (Page 65-69)